A seatbelt for a passenger vehicle typically has a seatbelt retractor that serves to retract the belt into its housing. The belt is wound upon a spool in the housing. When the belt is drawn or protracted from its housing, the spool winds a retraction spring, which later retracts the unused portion of the belt onto the spool or withdraws the belt into its housing when not in use.
In the event of a crash, the seatbelt retractor has a lock that prevents the seatbelt from extending further from its housing. The lock may be actuated by an inertial sensor, which responds to changes in vehicle speed during the crash. When a large deceleration is detected, the inertial sensor triggers the lock of the seatbelt retractor to lock the spool and thereby secures the safety belt in place during the crash.
The inertial sensor has an inertial sensor mass that moves in response to changes in speed of the vehicle. This mass is mechanically linked to the lock by an actuator. When the mass moves, the actuator moves and causes movement of a locking pawl that locks the lock when the mass has moved in excess of a predetermined amount. The actuator rests on a surface of the mass. This surface is angled so that movement of the mass causes rapid movement of the actuator and consequently the locking pawl. While rapid movement of the components of the inertial sensor and lock are desirable for safety, this same feature causes undesirable noise during normal vehicle operation.
A need therefore exists for a seatbelt retractor that reduces noise from the foregoing moveable parts.